Gastro-intestinal infections

Gastrointestinal infections are among the most commonly encountered infections in primary care. While they may not always be severe and may often resolve rapidly, they can be serious in specific healthcare settings or patient populations.

Gastrointestinal Infections

> 200 million episodes/year of infectious gastroenteritis in US1

Worldwide 3-6 million children die each year from infectious gastroenteritis2

Outbreaks of gastrointestinal infections are a serious concern in the hospital environment

Definition

Gastrointestinal infections are viral, bacterial or parasitic infections that cause gastroenteritis, an inflammation of the gastrointestinal tract involving both the stomach and the small intestine. Symptoms include diarrhea, vomiting, and abdominal pain. Dehydration is the main danger of gastrointestinal infections, so rehydration is important, but most gastrointestinal infections are self-limited and resolve within a few days. However, in a healthcare setting and in specific populations (newborns/infants, immunocompromized patients or elderly populations), they are potentially serious. Rapid diagnosis, appropriate treatment and infection control measures are therefore particularly important in these contexts.

Gastrointestinal infections can be caused by a large number of microorganisms, including:

Adenovirus

Adenovirus can cause diarrhea, fever, conjunctivitis, bladder infections and rashes, but the most common symptom is respiratory illness. After rotavirus, it is the most common cause of pediatric diarrhea.

Campylobacter

Campylobacter is one of the most common bacterial cause of gastroenteritis worldwide and is frequent in children under two. It can cause diarrhea (sometimes bloody), abdominal cramps, vomiting and fever. It is usually food-borne through raw or undercooked meat (especially poultry) or through contaminated milk.

Clostridium difficile

Clostridium difficile infection is responsible for up to 25% of cases of antibiotic-associated diarrhea most often contracted in hospitals or healthcare institutions3. Elderly and immunocompromized patients are most at risk. The recent emergence of highly toxigenic and resistant C. difficile strains has led to more frequent and severe outbreaks, increased morbidity and mortality.

Escherichia coli

Escherichia coli, often called E. coli, is the leading cause of travelers’ diarrhea and a major cause of diarrheal disease in the developing world, especially among children. People usually contract E. coli through ingestion of water contaminated with human or animal feces.

Escherichia coli O157:H7

Escherichia coli O157:H7 is a Shiga toxin-producing form of E. coli bacteria, which causes gastrointestinal infections with symptoms including bloody diarrhea and vomiting. Though it usually resolves after a few days, it can sometimes (5-10%4 of infections) lead to hemolytic uremic syndrome (HUS), which can result in kidney failure if untreated.

Helicobacter pylori

Helicobacter pylori, called H. pylori, is a cause of gastritis and is associated with the development of gastric and duodenal ulcers. It can cause stomach pain or nausea, but in many cases there are no symptoms. Infected people have a 10-20% lifetime risk of developing peptic ulcers and a 1 to 2% risk of stomach cancer5.

Rotavirus

Rotavirus is the most frequent cause of diarrhea in young children and infants and it is responsible for the most severe cases. There is a vaccine for rotavirus, but globally it causes more than ½ million deaths per year in children less than five years old.6 Most of these are in emerging countries.

Salmonella and Shigella

Salmonella and Shigella are food-borne GI illnesses. Salmonella is common and is found in raw meats, poultry, seafood and eggs, as well as milk and dairy products. Acute symptoms include nausea, vomiting, abdominal cramps, diarrhea, fever, and headache. Shigella is frequently found in water polluted with human feces. Symptoms of shigellosis (bacillary dysentery) include abdominal pain, cramps, diarrhea, fever, vomiting, and blood, pus, or mucus in stool.

Staphylococcus aureus

Staphylococcus aureus is the most common cause of food intoxication, characterized by abrupt/violent onset, severe nausea, cramps, vomiting, and diarrhea using lasting 1-2 days. This opportunistic pathogen can be found on humans (skin, infected cuts, noses and throats) and has been associated with a wide range of foods including meat and meat products, poultry and egg products, salads, bakery products, and dairy products.

Yersinia enterocolitica

Yersinia enterocolitica, called Y. enterocolitica, is a relatively infrequent cause of diarrhea and abdominal pain. Infection is most often acquired by eating contaminated food, especially raw or undercooked pork products, as well as ice-cream and milk. Common symptoms are fever, abdominal pain, and diarrhea, which is often bloody.

Diagnosis

When symptoms point to a possible gastrointestinal infection, diagnosis can be confirmed through laboratory tests used for culture or antigen detection from stool specimens. In certain cases (e.g. for E. coli, Salmonella, C. difficile …), antibiotic susceptibility testing is used to determine microbial resistance to antibiotic therapy, if appropriate. Particularly in hospital settings, rapid diagnosis provides important information for implementing infection control measures.

To diagnose the cause of a diarrhea, it is helpful to consider where the context is a food-borne outbreak or “travelers’ diarrhea”.

Food-borne outbreaks:

Often local – a group of people eating together suffer the same illness.

A public health concern when widespread, affecting people in different places and over a longer period of time.

Important to recognize and track epidemiologically, to prevent more people from being infected.

E. coli, Salmonella, Campylobacter and Staphylococcus are among the most common pathogens causing food-borne outbreaks.

Travelers’ diarrhea:

Most common travel-related illness.

Contracted by people travelling in places where there are different pathogens from what they are used to, especially in regions where food/water contamination is more prevalent.

Most commonly transmitted through ingestion of food or water contaminated with feces.

Most cases caused by bacteria including E. coli, Salmonella and Shigella.

Prevention / Treatment

The best ways to prevent gastrointestinal infection include:

Proper hand-washing

Disinfecting of contaminated surfaces with bleach

Washing of soiled articles of clothing

Identifying infected patients as soon as possible to implement extended infection control

There are no vaccines for most gastrointestinal infections. Exceptions:

Rotavirus

Adenovirus (limited availability)

For C. difficile: avoid prescribing antibiotics unnecessarily

Treatment measures for gastrointestinal infection include:

Rehydration – oral and sometimes intravenous

For many cases of bacterial gastroenteritis, only symptomatic treatment (for fever, diarrhea…) is required.

Antibiotics are not usually recommended as they have no effect on viral infections, may cause side effects and overuse increases the risk of resistant bacteria developing.

Antibiotics may be recommended in particularly severe cases of gastroenteritis, or if a specific bacteria has been identified as the cause.

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